Silicone elastomers, coatings and sealants along with other materials have received extensive evaluation and development in the National Institute of Neurological and Communicative Disorders and Stroke (NINCDS) Fundamental Neurosciences Program for use as electrical insulation for neural prostheses and devices. All materials still, however, exhibit unsuitable long term adhesion characteristics when exposed to the corrosive effects of body fluids and electrical stress. Additional failures of silicones in inflatable mammary prostheses and even aquarium sealants, point to certain types of oils and chemical bonds in the materials that should be avoided. Some primers contribute to adhesion retention when exposed to boiling water, others are detrimental. Although NINCDS funds two (2) programs on insulating materials and adhesion, these programs are hampered by the proprietary nature of silicones and other insulating materials.* Silicone systems will be studied starting with monomers, polymerization procedures, other chemicals and catalysts in an attempt to demonstrate suitable adhesion and stability by better control of the presence of oils, macrocyclics, crosslinkers, and ionizable atoms. Cyclic voltammetry will be used to evaluate the retention of adhesion of various silicone materials (elastomers and primers) bonded to the noble metals and other materials used in electrodes, leads and electronic packages. Polymerization methods and polymer purification procedures will selected to reduce the level of oils and contaminates. The completeness of cure and presence of oils will be monitored by Gel Permeation Chromatography. Successful demonstration of the causes of adhesion failure will allow for the demonstration of commercially useable insulators in a SBIR Phase II Program. As a consequence of being able to prepare devices suitable for long term implantation the NINCDS programs and the people they are attempting to help would all be immediate beneficiaries. *The proposed approach differs in that extremely pure silicone polymers corsslinkers and other ingrediants will be prepared for formulating into insulating materials.